The human auditory system is able to determine a location of sound sources by analyzing acoustic cues in the sound signals reaching the entrance of both ears. Acoustic cues (e.g., an interaural time difference (ITD) and/or an interaural level difference (ILD)) can result from the filtering of the sound signals by the listener's head, torso, and pinnae. This filtering behavior can be described in terms of a user's head-related transfer function (HRTF). Applying an HRTF to a 3D audio signal provides the user with the spatial cues necessary for reproducing spatial audio over headphones worn in, on and/or near the user's ear.